Ok, let’s put some numbers on the deal.
Toyota Prius with solar panels: yes, they exist.
A solar panel can give you 250 watts per square meter tops, at full sun power.
You can get 0.5 kilowatt tops under extremely brilliant sun with no clouds and assume you can use 2 square meters.
An electric motor for a car uses around 15 kwatt-hour for 100 km.
So, if a car has a 2 square meter solar panel getting sun for 4 hours-equivalent sun at 250 watts you can get 2 m2 * 0.25 kwatt * 4 hours = 2 kwatt-hour, which is enough energy for 12 km.
However, you can get that energy from a wall socket for 13 cents per kwatt-hour or 2 kwatt-hour * 0,13 dollars = 0,25 dollars, give or take.
The solar panels cost around 1 dollar per watt, so the panels you see on that roof cost 500 dollars
You would save 1 dollar per day, using 500 dollars in cost of capital.
Not a very good business, specially if you take in account that the panels are moving around at great risk of accidents or scratches or pebbles, things that do not happen in a house roof and that can ruin your investment in one second.
However, they look cool.
Moreover, if you radically redesign the car, you can lower the energy requirement and enlarge the area of panels.
You need a semi-car, quasi-vehicle, half-auto that weighs around 300 kg (a full sized car weighs more like 1.500 kg), has a frontal area of 1 point something square meter (instead of the 3 to 5 square meters of a regular car) and rides in Australia inclement sun.
In that conditions you can go at 95 kph, at speeds of a Trabant and probably with the same durability and safety in case of an accident
Sun races in Australia are very popular, or so I’ve heard in magazines like Popular Mechanics (but I also read there how to build a flying car, so you have that to take in account).
If the fires do not stop you, the light from the Australian burning bushes will take you far away by the mere power of light, so you can save koalas while you avoid crocodile attacks and run away from dingoes that want to gnaw your ankles…
bbabo.ℵet